High intensity lighting fixture



APri13Q1969 CJNTRATQR .1 3,437,802

HIGH INTENSITY LIGHTING FIXTURE Filed Dec. 11, 1967 Sheet of s INVENTOR.Cmews 011 mm April 8, 1969 c. INTRATOR 3,437,802

HIGH INTENSITY LIGHTING FIXTURE Filed Dec. 11, 1967 Shet 2 of 3 Z 4 i 73 g T 1 irfi. Z6 i 9- g 49 I INVENTOR. C'Hnmes fivnecme April 8, 1969 c.INTRATOR 3,437,802

HIGH INTENSITY LIGHTING FIXTURE i Filed Dec'. 11, 1967 .Sheet 3 of5 /T1' v Ti 14.. 47 47 c T g; v

I v ki INVENTOR. Cmyws llvrmme United States Patent 3,437,802 HIGHINTENSITY LIGHTING FIXTURE Charles Intrator, 31 Western Drive, Ardsley,N.Y. 10502 Continuation-in-part of application Ser. No. 556,130, June 8,1966. This application Dec. 11, 1967, Ser. No. 691,683

Int. Cl. G03b 15/02 US. Cl. 240-13 14 Claims ABSTRACT OF THE DISCLOSUREA lamp having a high intensity linear light bulb (e.g. having a colortemperature of over 3100 K.) mounted in the open angle of an L-shapedreflector whose planes are substantially parallel to the bulb. The sidesof the reflectors which face the bulb have satin surfaces thereon. Thereflector is carried on a support structure which is adjustably mountedon a channel having parallel bus bars. The parallel bus bars cooperatewith the support structure to electrically connect the light bulb to asource of potential.

This application is a continuation-in-part of my application Ser. No.556,130 filed June 8, 1966, now abandoned and incorporates the entiredisclosure thereof.

This invention relates to high intensity lighting.

In the lighting of motion picture and color television studios,extremely even lighting of the set is often required. At present, theindustry uses large dished reflector lamp units for this purpose,usually mounting a series of such units (e.g. circular, concave, M.R.Skypans 30 inches in diameter and dished about 4 inches) spaced 6 feeton centers, mounted on correspondingly large supporting yokes. Becausethese units are too big to be hidden by a conventional low ground rowthey cannot be used in the most desirable manner on the set, but areplaced where they can be hidden by the scenery. This, of

cluttering the studio floor have been very troublesome,

and color television and motion picture studios have tried hanging alltheir lights from the ceiling; as a result, there is a mass of tangledcables overhead, and expensive balancing rigs are needed to keep thelights in the proper position.

Another defect in present-day studio lighting is the fact that thelights suitable for this purpose decrease in color temperature (by asmuch as 300400 Kelvin in the course of a full shooting day). Such adecrease seriously affects the color rendition of scenes shot out ofcontinuity but which require matching later on.

One aspect of this invention relates to a new and improved lamp andlighting system which is suitable for lighting large areas to thedesired high intensity and at a color temperature required in colormotion picture and color TV studios.

One embodiment of the invention is illustrated in the accompanyingdrawing in which:

FIGURE 1 is a perspective view of a lamp and of a channel which servesas a support and as a source of electric power;

FIGURE 2 is an exploded perspective view of the lamp, without its bulb;

FIGURE 3 is a top view showing the transitory position of the lamp whenits conductive head is first inserted into the channel;

FIGURE 4 is a top view showing the final position of the lam clamped tothe channel;

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FIGURE 5 is a fragmentary side view taken with the parts in the positionshown in FIG. 3;

FIGURE 6 is a side view, with the channel shown in cross-section, withthe parts in the position illustrated in FIG. 4;

FIGURE 7 is a cross-section side view of the bulb and reflecting portionof the lamp showing the paths of light rays from the filament;

FIGURE 8 is a side view of a lamp having a modified form of mounting andalso fitted with a movable light shield or barndoor;

FIGURE 9 is a side view of a lamp showing a construction for mountingthe lamp on the channel so that it can be rolled along the channel;

FIGURE 10 is a perspective view showing the channel and lamp mounted ona movable stand;

FIGURE 11 is a side view illustrating the use of the lamps for lightingan indoor cyclorama;

FIGURE 12 is a perspective view illustrating the use of the lampsoutdoors, in sunshine;

FIGURE 13 is a plan view showing the placement of the lamps for atwo-wall cyclorama; and

FIGURE 14 is a view in elevation illustrating the use of the lamps oflighting a show window.

FIGURE 15 is a cross-section side view of a modified form of the lamp.

Turning now to FIG. 1 of the drawing, reference numeral 11 designates ahigh intensity light bulb, which preferably comprises an elongatedquartz envelope 12 within which there is a tungsten filament 13surrounded by an iodine atmosphere which prevents the blackeninginherent in many types of filament lamps. Such light bulbs are currentlymanufactured by the General Electric Company under the name Quartzline,and by other manufacturers, and are discussed, for example, in US Patent2,997,574, of Aug. 22, 1961, of W. I. Miskella. The bulbs I prefer touse are tubular bulbs operating under overvolted" conditions at a colortemperature of over 3100 K., e.g. 3150 or 3200 to 3450 K. For example, Ihave used bulbs whose quartz envelope has an external diameter of aboutinch and an overall length of about 4 to 10 inches, the lighted length(i.e. the length of the lighted filament which is centeredlongitudinally and radially in the bulb) being correspondingly about 3/2 to 9 inches and the wattage ranging from about 250 to 4000 watts.Typically, the temperature of the quartz envelope should be at about700900 F. during operation, to promote the tungsten filament-rebuildingetfect of the iodine atmosphere in the bulb so as to prevent blackeningof the envelope. The quartz envelope may be externally sandblasted andmay have a milky appearance.

In the illustrated embodiment, the bulb 11 is mounted at the open angleof a short section of extruded aluminum angle rod stock 14 having arms16 and 17 of equal length and about A; inch thick, made of high purityaluminum. Thisaluminum angle rod serves both to support the bulb and asa reflector.

The bulb holders 18 for the Quartzline bulb 11 may be of the usualcommercial spring loaded construction generally illustrated in thepreviously mentioned Miskella patent and may be supplied with electricpower through cables 19 (the electrical connections should be of a heatresistant type, e.g. welded, in view of the high temperatures prevailingin my lamp). These bulb holders may be fixed to the angle rod 14 in anysuitable manner; as illustrated, they are held by a pair of curvedclamps 21 each having its lower end riveted at 22 to the angle rod andits arcuate upper portion receiving the correspondingly shapedcylindrical bulb holder 18. Two spaced kerfs 23 are cut across the apexof the angle rod 14; each kerf receives a pair of supporting ears 24 ofone of the bulb holders 18. In one construction, the bulb 11 issupported with its center less than inch, preferably about /2 inch, fromthe nearest inner wall 26, 27 of the angle rod 14, these inner walls areeach about 2 inches wide (e.g. 178" wide), and the angle rod extendsabout 1% inches past each end of the bulb so as to accommodate theholders 18. An angle rod whose arms are more than about inch thick,preferably about A; inch thick, has given especially good results.

The angle rod 14 is supported by a clip structure indicated generally as28, to which it is pivotally attached through a bracket 29. Thus, thebracket 29 may be U- shaped with its center portion 31 riveted to theangle rod and its legs 32 apertured to receive aligned bolts 33 whichpass through depending ears 34 of the clip structure 28, the bracketlegs 32 and the ears 34 being separated by washers 36 to permit tiltingof the angle rod about a horizontal axis. An insulated handle 37 fixedto one leg 16 or 17 may be used for tilting the angle rod manuallyagainst the friction at the washers 36.

The inner walls 26, 27 of the angle rod 14 are close to the highintensity bulb 11, and become very hot, despite the high thermalconductivity of the aluminum. I have obtained best results in avoidingundesired hot spots, pitting and burning of the aluminum surface, and inobtaining an extremely even light pattern, by making the angle rod ofhigh purity aluminum and etching the aluminum surface (as with diluteaqueous chromic acid for a short time, eg a minute) to remove impuritiesand produce a very finely etched satin surface and wire brushing theetched aluminum surface of the inner walls in a direction transverse tothe length of the bulb 11 (as with a rotary brush having fine, crimped,stainless steel bristles). On such brushing, there are formed a seriesof more or less straight overlapping and intersecting fine shallowscratches and depressions (shown schematically at 38) extending in adirection generally transverse to the filament. I have found that asurface so treated, which has a soft, silky, satin appearance, performsbetter than a highly polished surface, or a commercially availablelenticular or specular surface. The scratches transverse to the filamentappear to serve to break up the linear light pattern. The angle rod 14,having been made by extrusion in conventional manner, may also have someshallow scratches or extrusion lines 39 running lengthwise of the bulbon its inner walls 26, 27 For best results, the inner walls should befree of organic material which will carbonize and darken under theintense heat of the bulb.

The quartz envelopes 12 of the linear Quartzline bulbs currentlymanufactured usually have a thickened portion or projection 41, at aboutthe middle of the envelope. For best results, the bulb should be mountedso that this projection, which can act as a heat-concentrating focussinglens, faces outward away from the angle between the walls 26, 27 (asindicated in FIG. 7).

The mass of the angle rod 14 is effective as a heat reservoir, whichhelps to stabilize the temperature of the quartz envelope of the bulb ata desirable level during use. The weight of a suitable angle rod, havingarms 1% inches wide and /8 inch thick is about lb. per inch of lengthand its heat capacity at high temperatures in the neighborhood of 500600C. is about 6 calories per inch of length. To help keep the angle rodfrom becoming too hot, there may be small vents in its upper surface;for example, the rivets 42 used for attaching the angle rod to theU-shaped bracket 29 may be hollow (see FIG. 7) and there may be a pairof holes 43 in the upper arm 17, preferably directly above the bulbholders 18, to promote heat dissipation through convection. The holes 43may, for example, be about /2 inch in diameter and so positioned as tohave little, if any, effect on the reflecting ability of the surface 27.The substantial absence of side enclosures helps dissipate the excessheat through air circulation. The outer surfaces 44, 45 of the angle rod14 may be blackened to increase the radiation of heat therefrom.

Tests on the lamps of this invention indicate that Quartzline bulbs canbe used therein effectively for pcriods well in excess of their ratedlife; in one test, the bulb was used in such a lamp for a period greaterthan twice the rated life and still gave a good high intensity light ofhigh color temperature.

In view of the high temperatures generated by the high intensity bulb11, special provision is made to prevent spalling at the washers 36. Ihave found it effective to treat copper washers with iodine, as byimmersing the washers for 5 minutes in a dilute solution of iodinecrystals in CCL, in an iron vessel. I have found that when suchsurface-treated Washers are used, there is sufficient friction (when thenuts 46 on the bolts 33 are tightened) to hold the lamp at any desiredtilt to permit the lamp to be tilted manually, and to maintain the lampin the new tilted position (without the need of loosening andretightening the nuts 46). Cadmium plated washers are also effective forthis purpose. The nuts 46 may be of well known heat-resistant type,having multiply-split necks (e.g. of the Flexlock type), and designed tooperate without annealing at high temperatures.

In use, the lamps of this invention are adjustably supported on a rigidconductive structure comprising a grounded channel 47 (FIG. 1), made ofhigh strength steel and open at the bottom, encasing two full-lengthsolid electrically conducting copper bus bars 48 (FIG. 6) electricallyinsulated from the steel channel by insulating strips 49. The channelsare made in, for example, S-foot lengths or 10-foot lengths, and longerchannels may be built up by connecting several lengths together. Thechannels may he supported in any suitable manner, as by means of hangers51, from the ceiling of the studio.

The clip structure 28 comprises a pair of opposed, offset, springy clips52 adapted to be snapped over the opposite sides 53 and top 54 of thechannel and having beads 55 for engagement in spaced longitudinaltroughs in the top 54 of the channel. Rigidly mounted between the clipsis the T-shaped head 56 of a casing 57 of strong electrical insulation(e.g. phenolic plastic) carrying a pair of spaced electrical contacts 58(which may be of silver-plated Phosphor bronze), which can be placed incontact with the bus bars 48 in a manner to be described below. Thedepending spaced ears 34, previously mentioned, are fixed to the clips52 and the cables 19 are electrically connected, Within the casing 57,to the contacts 58.

To engage the clip structure 28 with a channel 47, the top of theT-shaped head 56 is inserted into the opening at the bottom of thechannel at the desired point along the length of the latter. The partsare now in the position shown in FIGS. 3 and 5 with the contacts 58aligned longitudinally of the channel within the channel and the clips52 extending parallel to the channel in opposite directions at the sidesof the channel. The clip structure is then given a turn (about avertical axis); as shown in FIGS. 4 and 6, this compresses the contactsagainst the bus bars 48 and brings the clips firmly around the channelwith the beads 55 in the troughs thereof, so that the lamp is securelylocked to the channel and firmly supported in the desired position.

The channel 47 may also be mounted on a standard /8" stud lamp stand 59(FIG. 10) by the use of an adapter comprising a sleeve 61 (having a setscrew 62 to fix it to a stud 63), which sleeve has welded or brazedthereto a spring steel hanger 64 whose two arms 66 are adapted to snaparound, and hold, the channel 47.

The lamp illustrated herein projects the light evenly over a large areawith a fall-off in light intensity only at the outer sides. Thisfall-off in light level is desirable especially for lighting large flatareas. It enables the lighting director to overlap his units to achievean even distribu tion of light without the customary hot spots usuallyfound Where the outputs of the two units overlap. The

provision for tilting the reflector about a horizontal axis makes itpossible to direct the light at that point of the set where it will givethe most desirable lighting quality. At the same time, the light patternhas a sharp edge at the top and bottom, cutting off all spill asillustrated in FIG. 7 (which also shows the path of some of thereflected rays) and there is no need for the back baflles or teasersconventionally hung overhead to prevent light flares from adverselyaffecting photography or view.

The reflectors described herein have also been found to be extremelyeflicient. Thus, they have given an increase in light (measured in footcandles at a fixed distance from the bulb) of some 20% or more whencompared to commercially available reflectors (such as the ovalreflectors with lenticular surfaces) using the same bulb and samewattage.

FIG. 11 illustrates the use of the device in lighting a cyclorama 67 orother set in a studio. A cyclorama is a vertical background, usuallylight-colored and having a dull or matte surface, which when properlylit gives to the viewer of the motion picture or TV image an endlesseffect, that is, an effect of a deep background going off into the skywithout a horizon. With a typical cyclorama 14 feet high and 60 feetlong, a continuous channel 47 was mounted at a height of 14 feet,suspended from the ceiling C four feet away from the surface of thecyclorama and the lamps (having a 1000 watt Quartzline bulb in eachlamp) were attached 3 feet apart along the channel with the bulbs facingthe cyclorama. This gave a flat light evenly distributed at a level of500 foot-candles, without hot spots, over the upper four-fifths L of thecyclorama 67. When, in addition, the same number of lamps were installedon a channel 47 on the floor F (and hidden by a ground row 68) it waspossible to achieve extremely flat light distribution from top to bottomand end to end at an intensity of 700 foot-candles. The wattage used wasonly half the wattage required for producing acceptable light of muchless even distribution by the presently accepted practices in theindustry and there was no spill to interfere with the camera 69.

It will be appreciated that the most intense light is reflected from thecorner portion of the reflector, indicated on the drawing by thebrackets at C (FIG. 8) and that the middle part of the cyclorama, whichreceives this more intense light in the arrangement shown in FIG. 11, ismore distant from the reflector than the upper portion of the cycloramawhich receives the less intense light.

The ground row 68 may be a low barrier (e.g. about 6 inches high) havinga wavy, irregular upper edge to make it less visible in the finalpicture and usually painted to .blend with the scenery, as is well knownin the art.

For a cyclorama 67 made up of two vertical walls at right angles, thelamps may be mounted overhead as indicated, in plan view, in FIGURE 13.

The entire unit including channel and lamp occupies less than 5 inches(e.g. 4% inches) measured vertically. This leaves a great deal of roomfor any other lighting units 70 the lighting director may wish to use.With present-day systems which are much more bulky there is often aproblem because the presence of one lighting unit interferes with thelight pattern cast by another unit.

In order to control further the light pattern given off by the lamp, anadjustable baffle or barndoor 71 (FIG. 8) may be attached to one or bothlegs of angle rod 14, as by means of suitable friction hinges 72; thisenables the lighting director to mask any portion of the output of thelight deemed superfluous (as indicated by the paths of light rays inFIG. 8). The barndoor may be made of aluminum, whose surface may bepainted black. It may be of thin non-reflective sheet material.

FIG. 12 illustrates the use of the lamps of this invention for makingcolor movies in an outdoor location An important and recurrent problemin photographing exteriors, in sunlight, is the need for extremely highlevels of light on the order of 1000 to 4000 foot candles to balanceshadowed areas. Current practice is to use are lights of up to 225amperes, and/or 200010,000 watt incandescent spotlights. Through the useof the channelmounted lamps supported on stud lamp stands 59 andjudiciously spaced or hidden behind available props such as pillars,railings, etc., (indicated in dotted lines at 74) or even riggedoverhead, it becomes possible to get an adequate amount of fill lighteven on a bright sunny day, so that the shadows, cast by the subject 76in the light of the sun 77, are lightened. The actual amount of powerrequired under these conditions is reduced enormously by the use of thelamps of this invention.

FIGS. 8 and 9 illustrate variations in the mounting bracket. In FIG. 8there is an additional pivot point 78 permitting rotation of the lampabout a vertical axis. In FIG. 9 the clip structure is replaced by astructure including an insulated housing 79 having two sets of spacedwheels 81 which ride in grooves formed in the channel 47; the housingalso carries a pair of spring-loaded silverplated Phosphor bronzecontact shoes 82 which are pressed against the bus bars 48. This wheeledstructure may be inserted into the channel at one end thereof and can bemoved freely along the length of the channel.

FIG. 14 illustrates the use of the lamps for lighting of shop windows.Here there may be used three channels 47 carrying lamps turned at suchan angle that the bulbs would not be visible, at least at eye level,from the street 84 through the glass front 85. As illustrated, twochannels are mounted near the glass front 85, one near the ceiling andone on the floor, while a third channel is supported on the ceiling. Itwill be understood that channels may also extend vertically along theside of the glass front 85 to support additional lamps. My lightingsystem is particularly suitable for jewelry window displays since thelight gives an extremely specular, glittering effect on jewelry eventhough the lamps are several feet away; this eliminates the need forlights close to the objects, as now used in jewelry window displays. Inaddition, the use of my lighting system makes it possible to make greatvariations in the lighting pattern when the display is changed, withoutthe need for special electrical installations to reposition the lights,since (as previously explained) it is extremely simple to move the lampsfrom point to point on a channel or to remove, or add to, the number oflamps on a channel. Ordinary clear Quartzline bulbs (not overvolted) arepreferably used in this form of the invention.

In the improved version of the lamp shown in FIG. 15 the portion ofangle rod 14 which is most directly exposed to the radiant heat of thebulb 11 is covered with a thin layer of aluminum reflective sheeting 91having a diffuse reflective surface, preferably a layer of etched andanodized high purity aluminum sheeting which may, for example, be about0.02 inch thick. As illustrated in FIG. 15, this layer may be benteasily to approximately the same configuration as the rod 14 and (beingthin and ductile), may be folded over the edges of the rod, as indicatedat '92, 93 to keep it in place. I have found that this version of thelamp yields improved performance. The reflector surface is better; it itnot adversely affected by normal manual handling; fingerprints do notshow and the handled areas do not change their reflectivecharacteristics significantly on exposure to the heat of the bulb. Thereflective surface is readily and quickly repaired, at low cost, if itshould become damaged or contaminated by simply replacing the sheet 91by a new one. Also, with this modification it becomes practical to havethe reflective surface closer to the bulb; I find that having thatsurface even inch closer gives superior lighting.

In the version shown in FIG. 15, the rod 14 continues to serve as a heatsink. The sheet 91 preferably has vent holes 94 which are generallyaligned with the vent holes 43 of rod 14 to help keep the rod and sheetfrom becoming too hot.

To replace the sheet 91 one need merely push back the spring-loaded bulbholders 18 so as to provide a free path for the manual removal of thesheet, and then place a fiat unfolded sheet of the reflective materialof desired length and width across the rod 14 and (while the holders 18are in retracted position) and fold the sheet manually against the rod.It will be understood that a prefolded sheet may also be used. Asindicated in FIG. 15, the sheet need not conform precisely to thesurface of the rod.

It has been found most convenient to use a sheet 91 whose width (i.e.whose dimension normal to the plane of the paper in FIG. 15) is slightlyless than the distance between the supporting cars 24 (see also FIG. Theholders 18, when permitted to return to their extended positions,overlap the edges of the folded sheet and help to hold it in place.

For many purposes it is best to have the vertical reflective surfaceextend from the line of intersection of the reflective planes for agreater distance than the horizontal reflective surface to give a bettercutoff of the lighted area while supplying more reflected light; forexample, in FIG. the horizontal dimension may be about 3 inches. Thismay be accomplished, as illustrated, by using a rod 14 whose verticalarm 16 is three inches long and whose horizontal arm 17 is two incheslong (both arms being about 4; inch thick), but one may also use lightergauge material for the portion which is further from the bulb.

Except as described above, the version shown in FIG. 15 may be identicalin its construction and use with the embodiments described previously.It will be understood that the surfaces of the rod itself need not beetched and brushed.

One suitable material for the sheet 91 is an Alzak finished sheet suchas the grade sold as Alcoa Type 1 Diffuse, having a satin finish, madeby etching an alumi num alloy sheet, removing impurities from thesurface of the sheet to give a so-called superpurity surface (of e.g.99.9999% purity) and anodically oxidizing the surface to form a clearaluminum oxide coating (e.g. 0.1 mil thick) thereon.

For convenience, the terms photographing and camera have been usedherein to apply not only to photography in which a latent image isproduced on a film (for later development) but also to the production ofelectronic or magnetic images for live or taped television as by thewell known use of an image orthicon, plumbicon, etc. tube.

In the preferred use of the lamps, they are mounted so that thefilaments 13 are maintained substantially horizontal.

It is understood that the foregoing detailed description is merely givenby way of illustration and that many variations may be made thereinwithout departing from the spirit of the invention.

What is claimed is:

1. A high intensity lamp comprising a high intensity linear light bulbhaving a color temperature of 3100" K. to 3450" K. and having anelectrically heated light-producing filament enclosed in alight-transmitting envelope, said bulb being mounted in the open anglebetween two substantially plane metal reflectors of large heat capacityarranged in intersecting planes substantially at right angles to eachother and substantially parallel to said bulb, said reflectors havingsatin aluminum surfaces and having a thickness of at least of an inch,and being spaced less than about of an inch from the central axis ofsaid bulb, and means mounted on the rear side of the reflector forelectrically connecting the bulb to a power source and for mechanicallysupporting the lamp.

2. A lamp as set forth in claim 1 in which said reflectors and said bulbare mounted, in fixed relation, said means for connecting and supportingincluding a support structure having electrical contacts for engaging apair of elongated parallel bus bars, mounted in an elongated channel, toprovide electric current to energize said lamp, said support structurehaving means for engaging said channel to support said lamp on saidchannel, said channel-engaging means being constructed and arranged foradjustable positioning along the length of said bars and channel wherebythe position of said lamp may be readily shifted along said channel.

3. A lamp as set forth in claim 1, in which said aluminum reflectorcomprises two substantially plane etched reflecting surfacessubstantially at right angles to each other to form a linear corner withsaid bulb being mounted in the open angle of said corner with itssfilament about /2 inch from each of said surfaces.

4. A lamp as in claim 3, in which the reflector comprises an extrudedaluminum bar of L shaped cross section having a reflective surface sheetfolded to generally conform to the interior angle of the L, the edges ofthe sheet being folded over the ends of the arms of the L.

5. A high intensity lamp comprising a high intensity linear light bulbhaving an electrically heated light-producing tungsten filament enclosedin a tubular quartz envelope containing iodine, said bulb being adaptedto be operated at a color temperature of 3100 K. to 3450 K. said bulbbeing mounted in the open angle between two substantially plane metalreflectors of large heat capacity arranged in intersecting planessubstantially at right angles to each other and substantially parallelto said bulb, said reflectors having satin aluminum surfaces and havinga thickness of at least of an inch, and being spaced less than about Aof an inch from the central axis of said bulb, and means mounted on therear side of the reflector for electrically connecting the bulb to apower source and for mechanically supporting the lamp.

6. A lamp as set forth in claim 5, in which said bulb is mounted at theopen angle of an extruded aluminum angle bar whose bulb-facing wallshave said satin surfaces.

7. A lamp as set forth in claim 6, in which said bulbfacing satin Wallsare of thin reflective surface sheet material attached to=the bar.

8. A lamp as in claim 5, in which said reflectors are of thick metalhaving a thin reflective surface sheet material on the sides which facesaid bulb.

9. A lamp as in claim 5, in which the aluminum reflectors comprise athin reflective surface sheet in contact with a heavy aluminum backing,said aluminum backing weighing at least about & pound per inch oflength.

10. A high intensity lamp comprising a high intensity linear light bulbhaving a color temperature of 3l00 K. to 3450 K. and having anelectrically heated-light producing filament enclosed in alight-transmitting envelope, said bulb being mounted in the open anglebetween two substantially plane metal reflectors of large heat capacityarranged in intersecting planes substantially at right angles to eachother and substantially parallel to said bulb, said reflectors havingsatin aluminum surfaces and having a thickness of at least of an inch,and being spaced less than about of an inch from the central axis ofsaid bulb, and an adjustable non-reflective baffle on at least one ofsaid reflectors to mask off a portion of the light supplied by saidlamp.

11. A high intensity lamp comprising a high intensity linear light bulb,having an electrically heated light-producing tungsten filament enclosedin a tubular quartz envelope containing iodine, said bulb being adaptedto be operated at a color temperature of 3100 K. to 3450 K., said bulbbeing mounted in the open angle between two substantially plane metalreflectors of large heat capacity arranged in intersecting planessubstantially at right angles to each other and substantially parallelto said bulb, said reflectors having satin aluminum surfaces and havinga thickness of at least of an inch, and being spaced less than about ofan inch from the central axis of said bulb, and an adjustablenonreflective baffle on at least one of said reflectors to mask off aportion of the light supplied by said lamp.

12. A lamp as in claim 11 in which said bulb is mounted at the openangle of an extruded aluminum angle bar whose bulb-facing walls havesaid satin surfaces.

13. A lamp as in claim 12, in which said bulb-facing satin walls are ofthin reflective surface sheet material attached to the bar.

14. A lamp as in claim 13 in which said baflie is pivotally mounted atthe outer edge of one of said reflectors, the construction andarrangement being such that the lamp provides an unfocussed path for thelight transmitted directly from said bulb and the light reflected bysaid plane reflectors, said lamp being free of side enclosures thatinterfere with heat dissipation by convection and having a vent in atleast one of said reflectors.

References Cited UNITED STATES PATENTS Ayotte 24010.69 Olds 240-1.3Somes 240-3 XR Chadwick 24047 Weeks 24051.11 Falk 240103 10 NORTONANSHER, Primary Examiner.

U.S. Cl. X.R.

